1. Field of the Invention
The present invention relates to a forged seal imprint inspection method for inspecting whether a seal imprint on a document or the like is forged, and more particularly, a forged seal imprint inspection method for calculating characteristic values of a compared seal imprint on a document or the like to provide objective data for determining whether the compared seal imprint is forged and a recording medium.
2. Background of the Related Art
A seal has a seal face with a name of a person, a company or an organization engraved thereon and a seal imprint is a mark formed by putting red stamping ink on the seal face of the seal and pressing the seal on paper. Seals originated in Mesopotamia and they were made using stone, clay, bone, shells, etc. and used to indicate possessions of their owners. The seals have been used from Zhou dynasty in china. In Korea, seals of the period of Nacklang were excavated in the area near Daedong-gang and seals of Silla dynasty were discovered in Anapji. Presently, the seals are widely used as an identification means in Korea, Japan and China and used as a document acceptance confirmation means in the West. Since the seals are used for important transactions and identification, seal forgery is increasing.
In the past, a seal was stamped on semitransparent paper, the seal face was attached to a copy seal and the copy seal was manually engraved to forge the seal. However, this method is not currently used because there is a large error between the genuine seal and the forged seal. Recently, photolithography has been widely used. This method photographs a seal imprint formed by stamping a genuine seal and etches a metal plate or a resin plate to generate a copy seal. In this case, there is a large difference between the copy seal or a seal imprint formed using the copy seal and the genuine seal due to an error in the photographing process. According to another method, a seal imprint is scanned and printed on a film, and this print is attached onto a photoactive compound (PAC), printed and dissolved with a solvent to make a copy seal. This copy seal and seal imprints formed by stamping this copy seal are difficult to distinguish from a genuine seal and genuine seal imprints. However, even this copy seal has an error due to excessive or insufficient exposure, excessive or insufficient dissolving in the copying process.
With the development of computers, a method of copying a seal using a seal engraving machine has been proposed recently. This method is a kind of computer aided manufacturing (CAM) and scans a copied seal using a scanner. Then, the method inputs a scanned image to a computer, sets a material having the same size as the copied seal in the seal engraving machine, adjust the size of the material to the copied seal and inputs a command to the computer. Then, a drill or a laser connected to the computer engraves the material according to the input command. A forged seal manufactured by this method is very accurate, and thus there is barely difference between the forged seal and the copied seal. However, an error may be generated during the size adjusting operation or if the copied seal is not located in parallel.
A superimpose inspection method is widely used as a fake seal imprint detecting technique. The superimpose inspection method compares and observes fine scratches, concave portions and convex portions of a genuine seal imprint and a compared seal imprint using a device such as a microscope or magnifies a genuine seal imprint and a compared seal imprint under the same condition, superimposes the compared seal imprint on the genuine seal imprint and observes the seal imprints. While a photographic method using a negative film was widely used in the past, an image processing apparatus such as VSC5000 has been used these days. In addition, a method of manually tracing a compared seal imprint for comparison of contours and a method of extracting a contour through photographing have been used. However, the manual tracing may have a problem in the reproducibility of the process and the contour extraction requires a dedicated optical apparatus or a high-level photographic technique and a long working time. It is difficult for these methods to precisely observe seal imprints due to interference of letters, a depth difference in stamping ink, etc. Furthermore, the above methods inspect seal imprints with the human eye, and thus there is a difference between ordinary people and experts. Even the experts have to inspect seal imprints according to subjective judgment so that the experts may present different judgment results.